Quokkas are one of the smallest species of the marsupial macropod family, and weigh only five to 11 pounds (about the size of a domestic cat). They live in western Australia, and though they seem super cuddly and fun, they are ruthless survivors.

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Arctic foxes live — where else? — in the Arctic circle. They can survive in extreme temperatures as low as -58°F, and raise their young in systems of underground burrows that have been used by many generations of foxes.

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Sea otters live in kelp forests on the coasts of the Northern Pacific Ocean, and often hold hands to keep from drifting away from each other. They float on their backs to crack open shellfish with rocks, making them one of the few species of mammals to use tools.

Pygmy hippopotamuses spend most of their lives underwater, and weigh between 400 to 600 pounds (a regular hippopotamus can weigh as much as 6 tons). Native to the forests and swamps of West Africa, the World Conservation Union estimates that there are fewer than 3,000 pygmy hippos left in the wild.

Most hummingbirds are 3 to 5 inches long, with some weighing less than a penny. They live in the Americas, and can flap their wing 50-200 times per second and fly as fast as 34 miles per hour.

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Sea turtles live for up to 150 years, but throughout their whole lives, they remember the beach where they were born. They can weigh up to 400 pounds, and live in tropical and subtropical oceans worldwide.

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Black-footed cats are the smallest species of wild cat, weighing between 3 and 5 pounds. They live in southern Africa, and are both solitary and strictly nocturnal. The cats can kill as many as 14 small animals in a single night.

When a mandarin duckling hatches, its mother has to coax it to jump out of a tree. The colorful ducks live in southeast Asia, Great Britain, and some parts of North America.

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Bearded tamarin monkeys are squirrel-sized animals that are very social, and live in large groups in Peru and the southern Amazon Basin.

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Gold dust day geckos have toe pads with tiny lamellae — a type of plate-like structure — that allows them to walk on bamboo, glass, or climb trees. They average around 7 inches long, and live in parts of Madagascar and its surrounding islands.

Red pandas are very good at balancing thanks to their bushy tails, and their red-and-white fur helps them blend in with the trees in their natural habitat. You can find them in southern Tibet, India, Bhutan, the northern mountains of Burma, and in southwestern China.

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The American mink is very energetic, and highly adept at both climbing trees and swimming. They are also raised in fur farms, making the mink the most world's most frequently farmed animal for its fur, exceeding the silver fox and sable.

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Fennec foxes are playful and social creatures that live in the sandy Sahara and North Africa. They are the smallest of the world's foxes at 9-16 inches, and use their 6-inch-long ears to radiate body heat and keep cool.

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Bottlenose dolphins are extremely charismatic, loyal, and highly intelligent. They communicate with their large pods using a complex system of squeaks and whistles, and use echolocation to find their prey by making 1,000 clicking noises per second.

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Northern pygmy owls are a mere 2 inches tall when they hatch, and only grow up to 6 inches. They live in North and Central America, and are very hard to spot in the wild due to their size and coloring.

Gray wolves travel in packs, typically with a mated pair and their offspring. They are an ancestor of the modern dog, and can eat between 20 and 30 pounds of meat in one meal. Today, gray wolves live in parts of Canada, North America, Europe, and Asia.

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Wombats are a solitary and pudgy nocturnal marsupial. They live in Australia's grasslands and eucalyptus forests in burrows and tunnels that they dig with their claws.

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Little blue penguins are only about a foot tall, making them the smallest species of penguin in the world. They live in New Zealand, the Chatham Islands, and southern Australia, with chicks often returning to within a few meters of where they were raised and settling there.

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Balloonfish can be found worldwide in tropical waters from the west coast of Africa to the Galapagos Islands. When it's threatened, the balloonfish can inflate its body by taking in water or air and increasing its diameter by as much as three times.

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Sea lions are intelligent and highly trainable, and were even taught by the U.S. Navy to detain scuba divers. They live in subarctic to tropical waters in oceans worldwide, feasting on meals that are typically 5-8% of their body weight.